Removal of cadmium from zinc ores.



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irsaisra isssrssuur GILBERT RIGG, OFPALMERTON, PENNSYLVANIA, ASSIGNQR T0THE NEW JERSEY ZINC COMPARE, 02 NE? YORK, N. 2., A CORPORATIGN OE NEVVJERSEY,

REMGVAL 0F CADMIUM FROM ZINC GEES.

masses.

No Brawl-a To (ZZZ icrznm it may) concern Be it known that l, GILBEHTRico, a subject of Great Britain, residing in Palmer ton, county ofCarbon, and State of Pennsylvania. have invented certain new and usefulImprovements in Removal of Cadmium from Zinc Ores; and l do herebydeclare the following to be a full,'clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

El i 5 invention relates to certain new and useful improvements in theran-oval of cadmium from Zinc ores.

The invention is based upon the discovery that when a zinc. orecontaining cadmium oxid is lixiviated with Water containing sulfuricacid in amount sufiicient to convert the cadmium oxid present intocadmium sulfate, the sulfuric acid will have a selective action upon thecadmium Moreover, even where the sulfuric acid radical is alreadycombined with the zinc, as, for instance, in roasted zinc ore theleaching of such ore with Water I have found to be accompanied with theyielding up of its S0, to the cadmium oxid, with the formation ofcadmium sulfate and its leaching out, as such, from the roasted ore.

In the practice of the invention I may take, for instance, a zinc oreroasted to a degree beyond a suliatizing roast, that is to say, so as toleave in the roasted'product not more than the usual amount of Zincsulfate incident to the roasting operation. By leaching the roasted zincbra with Water preferably at or near the boiling point, it will usuallybe found that the small amount of zinc sulfate usually present in theroasted ore will snilice. when brought into solution by the hot leachingwater. to convert the cadmium oxid present into cadmium sulfate, which,being likewise soluble in the ligiviating agent will be removed from theore.

In carrying out the leaching operation, it will be preferable to firstrun the hot leaching'liquid into the leaching rat and to then admit theore gradually, so that the anhydrous zinc sulfate shall go the morereadily into solution. Gtherwise, that is to say, if the ore were firstformed into a bed in the leaching rat and the leaching liquid thenpoured upon it there would be a tendency for the anhydrous zinc sulfate,in combining Specification of Letters Eatent.

Patented 2, 1-5915.

applicafion filed December 3, 1914. serial K0, 875,248.

with the water to crystallize in the mass of ore, and to act as abinding agent, thus interfering with the orderly and quantitativeprogress of the operation. The use of hot- Water is particularly to berecommended for the reason that zinc sulfate upon whose presence thecome sion of the cadmium depends is relatively highly soluble in waterat high temperatures. If the amount of zincsulfase present isinsufhcient to convert all of the cadmium oxid into cadmium sulfate, anamount of sulfuric acid or an amount of zinc sulfate he added theleaching Water to make up for the d i ciency, Whether it be large orsmall. In op erating upon natural oxidized ores, such as the carbonateor the silicate, the lixiviating water should contain a suiiicientamount of sulfuric acid to bring about the desired reaction.

it will, of course, be understood that whatever portion of the cadmiumof the roasted ore is already present therein as cadmium sulfate willrequire no conversion and ill he leached out with the converted portion.

From the foregoing description, it will he noted that the object or" theinvention is to abstract the cadmium from a cadmium-bearing Zinc ore. itis roasted, under proper conditions, to leave in the ore a limited quaty of i e sulfaie, so that, upon llXlYlSllOf: with fer, the zinc sulfatewill 'go into solution and convert the cadmium oxid present into cadmiumsulfate which will thereupon enter into solution. ll here. the quantityof zinc sulfate in the roasted ore is too small. it may be supplementedby adding zinc sulfate or by adding sulfuric acid, as the case maybe, tothe lixiviating Water. ll herc the ore treated is a natural oxidizedore, the necessary amount of zinc sulfate for effecting the conversionof the inscluole cadmium oxid into calcium sulfate any be produced ashereinbcforo indicated, by adding asulficient quantiuy of sulfuric acidto the lix.-

iviatin g water.

' lVhat I claim is:

Whcn the zinc ore is a suliid cient to convert the cadmium to be removedinto soluble cadmium sulfate, and -d,:'awing off the resulting solutionfrom the ore; substantially as described.

3. The method of removing 7 cadmium from zinc ores, which consists infirst roasting the ore, and lixiviating with water in the presence ofzinc sulfate in amount sufiicient to convert the cadmium to be removedinto soluble cadmium sulfate, the zinc sulfate presentbeing derived inpart from the roasted ore and 111 part from the addition or sulfuricacid to the lixiyiating Water, and

drawing oil the resulting solution from the ore; substantially asdescribed 4. The method of removingv cadmium from zinc ore, whichconsists in leaching the pro with ater 1n the presenceof a SllfilClGIltamount of zinc sulfate to convert the cadmium to be removed into solublecadmium sulfate, the leaching being efiected .by a lding the oregradually to a body of the leaching liquid, and drawing ofithe result:

ing solution from the ore; described. l v t V In testimc y whereofIaflix my in presence 'ofitwowitnesses.

GILBERT more.

substantially as signature,

Witnesses:

C. F. BmRBAUnR, E. G. TACY.

